Kinematics In the previous two chapters, we have considered the motion of a particle or a rigid body with respect to a system of fixed coordinate axes. In practice however, we often observe the motion with respect to a moving body. For example, we observe the motion of an flying airplane from a moving car, or observe the motion of raindrops from a traveling train. Why do obtain different results when we observe the motion a object on different coordinate systems or reference objects? It is known that there may exist relationship between two different objects. Next, we are going to study the relationship between the motions of an object and the reference object. First of all, we begin with the introduction of some concepts 88-1 concept of compositive motion of a particle 1. Coordinate system 1) Static coordinate system: A coordinate system fixed to the earth ground is called Static coordinate system SCs). 2) Moving coordinate system: A coordinate system fixed to a moving object relative to the earth ground is called moving coordinate system MCs). Forexample, a running car.5 §8-1 concept of compositive motion of a particle 1．Coordinate system： 1) Static coordinate system: A coordinate system fixed to the earth ground is called Static coordinate system (SCS). 2) Moving coordinate system: A coordinate system fixed to a moving object relative to the earth ground is called moving coordinate system (MCS). For example, a running car. In the previous two chapters, we have considered the motion of a particle or a rigid body with respect to a system of fixed coordinate axes. In practice, however, we often observe the motion with respect to a moving body. For example, we observe the motion of an flying airplane from a moving car, or observe the motion of raindrops from a traveling train. Why do obtain different results when we observe the motion a object on different coordinate systems or reference objects? It is known that there may exist relationship between two different objects. Next, we are going to study the relationship between the motions of an object and the reference object. First of all, we begin with the introduction of some concepts